one more question concerning "taper crimp"

the goal of handloading is to make every step the same so the end product is as close to being the same as possible because the goal is to put all the bullets in the same place on the target.

case lengths and case wall thicknesses can vary a lot so the case bell from the expand/bell step can vary a lot. the crimp (or debell) step will make the case mouth o.d. (outside diameter) the same for all your loaded ammo. just a good habit to get into, imo.

luck,

murf

call1911 said:

Good point - the press I'm talking about is a Forster Co-Ax. To your point about the "free TC" when using single-stage press and 3-die set: I never could warm myself up to seating and crimping in one step. The pure thought of pushing the bullet in the case and at the same time applying the crimp? Not good.

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Are you sure you're not thinking that way because you were told to think that way ? There's a huge difference here between "warming up to" versus loading 20 rounds both ways and then actually testing to check for significant changes.

What powder and OAL you will use is part of the Art of reloading. But whether taper crimp is 'needed' or 'beneficial when applied during seating', that can be measured.... which makes it part of the Science of reloading. So in the end you're asking for opinions on something you can measure for yourself.

Just another idea.

So, the oldest advice I (and an old fart I am) was given concerning taper crimping was to mic the bullet. Let's use .355 as an example. Then mic the case wall x 2. So, if the mic shows .012 for thickness right at the mouth rim then multiple by 2 for both case sides or .024 in this case. Add .355 and .024 and you have .379. This should give you a measurement as a baseline. These days, I just mic the casing up at the mouth as it comes out of the sizing die, add .003 to .005 at the expander depending on what type of bullet I'm loading, and then just remove the flare at the seating die. My groups look much like Walkalong's. When I do my 2-year re-qualifier for my CCW, they keep telling me to spread my shots out so they can count them instead of punching a fist-size hole in the center of the paper. Ha! I love watching chunks of paper fly!

Look at the attached chamber drawing. The dimension of the chamber where the case mouth would be is .381, but look down at the notes and you'll see that all diameter dims have a tolerance of +.004. So, the minimum chamber cut out at the mouth is .381, and the maximum .385. Your firearm will fall in between somewhere and you'll have to build your ammo to suit.

If you end up with .378 to .382 (bullet diameters vary as do cases thicknesses), then you're good.

If along the test I get problems with function or bullet setback I'll stop immediately because it's obviously better to taper crimp

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Do you really think that hasn't been done 100 times by early reloaders who (nearly) all came to the same conclusion that it is more safe to crimp? Some things that the books and experienced reloaders tell me, I take on faith. It only takes one round where the bullet setback was excessive to blow up your pistol in your hand.

berettaprofessor said:

Do you really think that hasn't been done 100 times by early reloaders who (nearly) all came to the same conclusion that it is more safe to crimp? Some things that the books and experienced reloaders tell me, I take on faith. It only takes one round where the bullet setback was excessive to blow up your pistol in your hand.

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I learned the hard way about heavy taper crimping your 9mm. repeated loading and unloading my 9mm carry, then one day the bullet fell out and got powder all over the action. my crimp now is so heavy, it dents the bullet

Mark_Mark said:

I learned the hard way about heavy taper crimping your 9mm. repeated loading and unloading my 9mm carry, then one day the bullet fell out and got powder all over the action. my crimp now is so heavy, it dents the bullet

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If you're carrying reloads for CCW, I would suggest that you search this site for "reloads for self-defense".

NMexJim said:

If you're carrying reloads for CCW, I would suggest that you search this site for "reloads for self-defense".

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Thanks! I’ll check it out. I load for uspsa and never really needed a heavy tapper crimp... until my ammo separated and spilled powder. Lesson learned

Mark_Mark said:

Thanks! I’ll check it out. I load for uspsa and never really needed a heavy tapper crimp... until my ammo separated and spilled powder. Lesson learned

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Under the Legal Forum, find "The Peculiar Problem of Handloads for Self Defense" by Spats McGee

NMexJim said:

Under the Legal Forum, find "The Peculiar Problem of Handloads for Self Defense" by Spats McGee

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thank! but I could care less about legality if I’m fighting for my life or my family’s life

Mark_Mark said:

Thanks! I’ll check it out. I load for uspsa and never really needed a heavy tapper crimp... until my ammo separated and spilled powder. Lesson learned

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I’m not sure what caliber you’re loading, but if we’re talking taper crimps, it’s not the crimp that holds the bullet, it’s proper neck tension from a proper sizing operation. If bullets are separating from the case, you may want to check neck tension and also your COL. I’ve seen where a too long COL will allow the bullet to engage the rifling and then an unload will pull them apart. Good luck.

Most 9mm bullets have no crimping groove (cannelure). So what is a crimping die of any sort doing? At minimum, its removing the bell you created in order to easily seat the bullet. At most it is also restoring the .010ish taper of the case for more reliable feeding.

The proof is in the shootin'. If they load, feed, fire, and cycle ok.... have reasonably good accuracy.... I don't see any harm. The "crimp" is not going to prevent bullet setback. Proper expanding (not over expanding) will do that.

Have just started loading 9mm a little bit lately. Understanding that the inside of the case is tapered, as well as the outside is enlightening to me. Essentially, your pushing a bullet with square edges into a hole that's getting smaller as it goes deeper.

Even if there wasn't a bell to get rid of wouldn't the neck tension at the bottom of the bullet be more than the neck tension at the rim?

It's obvious to me that less is more with this cartridge but I think I'll keep taking the bell out, plus just a tiny bit extra.

Walkalong said:

Actually, the ID of the case is getting bigger the deeper the bullet goes, assuming the sizer is tapered correctly, like some re, but many are not, so......

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There was a cutaway picture way back that made me think that but same idea...tapered inside and out.

chamokaneman said:

Have just started loading 9mm a little bit lately. Understanding that the inside of the case is tapered, as well as the outside is enlightening to me. Essentially, your pushing a bullet with square edges into a hole that's getting smaller as it goes deeper.

Even if there wasn't a bell to get rid of wouldn't the neck tension at the bottom of the bullet be more than the neck tension at the rim?

It's obvious to me that less is more with this cartridge but I think I'll keep taking the bell out, plus just a tiny bit extra.

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Think "interference fit" down below the flare. The bullet pushes out the case a couple of thou. That's where neck tension comes in.

Thomasss said:

It's six of one or a half a dozen of another as the saying goes. With many light or even medium loads lack of crimping is not a problem. Crimping becomes a problem when the bullet shifts position after the preceding cartridge is fired. Bullets can come out of the case and spill powder all over the place inside the gun plus the bullet can get stuck in your barrel (and you may not realize it). Or bullets can get seated deeper in the case and spike the pressure on the next round fired. Either situation is a big no no. Crimping whether you need or not just solves those issues and you don't have to worry about it.

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Semi-auto handloaded cartridges do not use a crimp to hold the bullet in place. Neck tension is sufficient, and designed in the sizing dies...